1. Field of the Invention
The present invention relates to a method and an apparatus for producing a toothbrush comprising a handle, a brush head and a plurality of bristle bundles, at least said brush head consisting partly of a first and partly of a second component.
2. Brief Description of the Prior Art
In the production of toothbrushes, it is known to produce the brush head from a hard component by injection moulding, said brush head being provided with blind holes into which the bristle bundles are pressed with the aid of the so-called anchor method. Furthermore, the so-called anchorless method is known in the field of toothbrush production; in the case of this method, the bristle bundles are encompassed with a hard-elastic plastic material by injection moulding. The hard-elastic plastic material has the effect that the bristle bundles cannot easily be drawn out of the brush head. In addition, the hard-elastic component essentially determines the elastic behaviour of the brush head. In the case of toothbrushes it is, however, desirable that the brush head has bristle sections of a comparatively low relative stiffness and bristle sections of a comparatively high relative stiffness. This aim could be achieved by using bristle bundles having different degrees of stiffness. The use of different bristles on a toothbrush, however, means that the production expenditure will be increased substantially.
It is therefore the object of the present invention to provide a method of producing a toothbrush of the type mentioned at the start in the case of which the brush head and/or the bristle bundles accommodated therein have improved elastic or stiffness properties and which allows a wide variety of different brush head designs. It is a further object of the present invention to provide an injection-moulding means for producing a toothbrush of the type mentioned at the start by means of which a toothbrush can be produced at a reasonable price, allowing the brush head of said toothbrush and/or the bristle bundles accommodated therein to have improved elastic or stiffness properties, and to allow a very variable design of the brush head and bristle accommodating structures.
The first-mentioned object is achieved by a method of producing a toothbrush comprising a handle and a brush head, which is provided with a plurality of bristle bundles, at least said brush head consisting of at least first and second components, comprising the following method steps:
injection moulding a basic body of a brush head from a first component in a first mould cavity, the bristle bundles being embedded at their ends into at least one bristle-bundle holding section consisting of said first component and said bristle-bundle holding section being connected by at least one bridge portion with the other areas consisting of said first component, cutting off the bridge portion between the bristle-bundle holding section and the other sections, changing the mould cavity, the second mould cavity being larger than the first mould cavity in the area of the bristle-bundle holding sections, and encompassing the bristle-bundle holding sections, which consist of said first component with a second component by means of injection moulding.
Preferably, the first component is a hard component while the second component is a soft component.
The second object mentioned is achieved by an injection-moulding means for producing a toothbrush, comprising an upper mould component and a first lower mould component defining together a first mould cavity for injection moulding a basic body of a brush head, wherein at least one movable mandrel is provided in said first mould cavity, said mandrel comprising first means causing the formation of at least one bridge portion between injection-moulded bristle-bundle holding sections during the injection-moulding process, and that the mandrel comprises second means which will cut off the bridge portion when said mandrel is moved in a predetermined manner.
Preferred embodiments are laid down in the dependent claims.